* Update setup.md
Detail that the stripe key must be commented out in order to create a dummy invoice
* Update create_invoice.py
Remove the example invoice function as the 'else' statement already captures this
* Update setup.md
Edited verbiage for the create invoice explanation
* cover empty stripe api env
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Co-authored-by: Dallas Young <33672687+dallastexas92@users.noreply.github.com>